From 23d402d42beb975b97303beb3d9d4f60f4a1a883 Mon Sep 17 00:00:00 2001
From: Alberto Garcia <berto@igalia.com>
Date: Fri, 28 Oct 2016 10:08:04 +0300
Subject: [PATCH] block: Add block_job_add_bdrv()

When a block job is created on a certain BlockDriverState, operations
are blocked there while the job exists. However, some block jobs may
involve additional BDSs, which must be blocked separately when the job
is created and unblocked manually afterwards.

This patch adds block_job_add_bdrv(), that simplifies this process by
keeping a list of BDSs that are involved in the specified block job.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 blockjob.c               | 17 +++++++++++++++--
 include/block/blockjob.h | 14 ++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/blockjob.c b/blockjob.c
index 7c88b30074..422851fde5 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -113,6 +113,13 @@ static void block_job_detach_aio_context(void *opaque)
     block_job_unref(job);
 }
 
+void block_job_add_bdrv(BlockJob *job, BlockDriverState *bs)
+{
+    job->nodes = g_slist_prepend(job->nodes, bs);
+    bdrv_ref(bs);
+    bdrv_op_block_all(bs, job->blocker);
+}
+
 void *block_job_create(const char *job_id, const BlockJobDriver *driver,
                        BlockDriverState *bs, int64_t speed,
                        BlockCompletionFunc *cb, void *opaque, Error **errp)
@@ -150,7 +157,7 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
     job = g_malloc0(driver->instance_size);
     error_setg(&job->blocker, "block device is in use by block job: %s",
                BlockJobType_lookup[driver->job_type]);
-    bdrv_op_block_all(bs, job->blocker);
+    block_job_add_bdrv(job, bs);
     bdrv_op_unblock(bs, BLOCK_OP_TYPE_DATAPLANE, job->blocker);
 
     job->driver        = driver;
@@ -189,9 +196,15 @@ void block_job_ref(BlockJob *job)
 void block_job_unref(BlockJob *job)
 {
     if (--job->refcnt == 0) {
+        GSList *l;
         BlockDriverState *bs = blk_bs(job->blk);
         bs->job = NULL;
-        bdrv_op_unblock_all(bs, job->blocker);
+        for (l = job->nodes; l; l = l->next) {
+            bs = l->data;
+            bdrv_op_unblock_all(bs, job->blocker);
+            bdrv_unref(bs);
+        }
+        g_slist_free(job->nodes);
         blk_remove_aio_context_notifier(job->blk,
                                         block_job_attached_aio_context,
                                         block_job_detach_aio_context, job);
diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index 2bb39f4d29..4dfb16b43f 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -188,6 +188,9 @@ struct BlockJob {
     /** Block other operations when block job is running */
     Error *blocker;
 
+    /** BlockDriverStates that are involved in this block job */
+    GSList *nodes;
+
     /** The opaque value that is passed to the completion function.  */
     void *opaque;
 
@@ -252,6 +255,17 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
                        BlockDriverState *bs, int64_t speed,
                        BlockCompletionFunc *cb, void *opaque, Error **errp);
 
+/**
+ * block_job_add_bdrv:
+ * @job: A block job
+ * @bs: A BlockDriverState that is involved in @job
+ *
+ * Add @bs to the list of BlockDriverState that are involved in
+ * @job. This means that all operations will be blocked on @bs while
+ * @job exists.
+ */
+void block_job_add_bdrv(BlockJob *job, BlockDriverState *bs);
+
 /**
  * block_job_sleep_ns:
  * @job: The job that calls the function.